5 research outputs found
Investigation of metal-rich half-Heusler thermoelectrics : synthesis, structure and properties
Thermoelectric materials that can directly convert heat into electricity offer a possible
avenue to address the world’s increasing demand for energy. Metal-rich half-Heusler
compounds are of interest due to their favourable electronic transport properties.
Unfortunately, widespread application is limited by comparatively high thermal
conductivity.
The effect of processing and excess metal (Ni and Cu) on thermoelectric properties of
MNiSn, M0.5M’0.5NiSn (M = Ti, Zr, Hf) and Ti0.5Zr0.25Hf0.25NiSn materials was
investigated and is discussed in Chapters 3 and 4. This work revealed that Cu is effective
n-type dopant, which improves electronic properties of half-Heusler materials. Detailed
structure analysis, which included high-resolution synchrotron X-ray diffraction, neutron
powder diffraction and electron microscopy revealed that most of the excess metals are
randomly distributed on the interstitial sites, producing significant point defect scattering
of phonons. In addition, Cu segregation leads to grain-by-grain compositional variations,
with grains tending towards either half-Heusler or full-Heusler composition.
In addition to the microstructural and properties studies, an in-situ neutron powder
diffraction experiment was used to understand the formation of Ni-rich TiNi1+ySn (y = 0,
0.075 and 0.25) and multiphase M0.5M’0.5NiSn compositions during solid-state reaction.
As described in Chapter 5, the half-Heusler formation occurs through a complex,
multistep reaction, which involves many intermediates. ZrNiSn and Ti0.5Zr0.25Hf0.25NiSn
underwent spontaneous self-propagating combustions, which is a new route to prepare
impurity-free half-Heusler alloys.
The last results Chapter describes the analysis of neutron total scattering data using
Reverse Monte Carlo modelling. This study was performed to gain insight into spatial
distribution of excess Ni within the half-Heusler structure. It confirmed random
distribution of excess metal on the interstitial sites
Polish version of the Cognitive Distortions Scale (CDS): Preliminary validation and personality correlates
BackgroundThe aim of the two research studies presented in this article was to test the reliability and validity of the Polish version of the Cognitive Distortions Scale (CDS). The relation of the CDS to psychological measures of well-being and other theoretically relevant variables was also explored.Participants and procedureTwo correlational studies were conducted with psychology undergraduate students and their family members (n = 196 and n = 90, respectively). Participants completed a paper-pencil set of questionnaires that contained measures of cognitive errors (study 1) and scales related to perceived quality of life and psychological well-being (study 2).ResultsPreliminary results supported the reliability of the Polish version of CDS (with Cronbach’s α .91 and .90) and convergent validity as indicated by correlations with maladaptive self-views and perceived relationship quality.ConclusionsThe Polish version of CDS appears to be a reliable and valid measure of cognitive distortions